1. Field of the Invention
This invention relates generally to electrical conduit box bodies for connecting conduits, and more particularly to improved electrical conduit box bodies having conduit connecting stub or hub portions adjoined to the chamber of the body portion by a large radius that eliminates sharp corners at the intersection of the hub passageways with the body chamber and provides a maximum radius of curvature for wire or cables pulled through or passing through the chamber and stub or hub passageways.
2. Background Art
Building codes require most electrical wiring to be enclosed in electrical conduits that may be connected to each other by way of electrical conduit boxes, junction boxes, or outlet boxes. The prior art type of conduit fittings or conduit box bodies which are pertinent to the present invention are known to those in the trade as “conduit bodies”, some of which are recognized by tradenames such as “Unilets®” (Appleton Electric Co., Chicago, Ill.) and “Condulets®” (Crouse-Hinds Company, New York, N.Y.).
Such conduit boxes, junction boxes, outlet boxes, Unilets®, Condulets®, or conduit bodies typically have a generally oblong hollow rigid body defining a chamber with one open longitudinal side and spaced tubular “stubs” or “hubs” extending perpendicularly outward from the body at various locations, usually along loci separated by either 90° or 180°. The interior of the body and tubular stubs or hubs are accessible through the open longitudinal side of the box, and the open side of the body is closed by a removable cover plate, typically attached to the body by screws, and may include gasket for weathertight sealing.
The interior of the tubular stubs or hubs define a passageway communicating with the chamber defined by the body, and their outer ends are typically internally threaded for connection to conventional electrical conduits. Insulated wires or cables extend through the conduit into the body chamber where they may be spliced or joined. These insulated wires are designed to carry relatively high voltages and currents (carrying 0 up to 2000 volts and 0 up to 750 amps). Theses conduit bodies may also be used for conduit containing optic fibers and/or signal or control wires (i.e., wire operating at a lower voltage with a maximum of 110 volts down to millivolts, serving to actuate switches and thermostats, or, in the case of telephone and data, wire for communications and computers).
The bodies of these conduit boxes serve as pulling fittings and are designed, for example, for wire pulls such as straight wire pulls, angled wire pulls and Y wire pulls, and for making bends or sharp changes in the direction of the conduit system or “run”. In this regard, conduit bodies are to be contrasted with elbows, which are bent portions of conduit. Electrical outlet boxes or “conduit bodies” are assigned various type designations (e.g., C, LB, LR, LL, T and X) depending on the number and locations of the conduit connecting stubs or hubs, and their size is designated by “hub size” (the size of the conduit connection—e.g., ½″ through 4″).
A common problem with conventional prior art conduit bodies, junction boxes, outlet boxes, Unilets®, and Condulets® is that the tubular stubs or hubs are very short and their length is governed by the optimal thread length required for thread engagement of the threaded ends of the conduit. Typically, the juncture of the interior of the tubular stubs or hubs with the interior of the chamber of the body is a relatively sharp corner at the transition surface where making a 90° angle, and no provision is made for providing a large transition radius for pulling wires or cables from the electrical conduit through the bodies. Thus, the electrical wires or cables are often damaged or seriously degraded when pulled over the relatively sharp corners encountered in the prior art conduit box fittings.
Bing, U.S. Pat. No. 6,580,029 discloses an electrical and telecommunications conduit body for connecting conduits. The conduit body includes an inwardly curved guide surface disposed between the chamber ends of the hub passageways, which functions to maintain a minimum radius of curvature of cables passing through the passageway defined by one hub and then through the chamber defined by the body to the other hub passageway so as to avoid pulling the cables over sharp corners at the intersections of the hub passageways with the body chamber. The guide surface may be a raised hump or in inwardly curved portion of the bottom wall or side wall of the body disposed adjacent to the perpendicular hub which extends inwardly into the body chamber toward the center of body and has a radius of curvature sized to provide a minimum radius of curvature for optical fiber cables prescribed by telecommunications industry standards (BICSI). Alternatively the minimum radius guide surface may be formed on a separate member that is inserted into the chamber of conventional conduit bodies. These configurations are undesirable since they reduce the volume and working space of the interior chamber.
Wagganer, U.S. Pat. No. 6,069,317 discloses an improved junction box for perpendicularly conducting stiff electrical cable, wherein the improvement includes one removable end wall of the housing that is replaceably attached to the base and side walls of the elongate housing. When the cover and end wall are removed, a clear passage is provided to facilitate running stiff electrical cable through the perpendicular stub or hub and bending it perpendicularly through the housing.
Bozdeck, U.S. Pat. No. 4,936,478 discloses a universal conduit fitting for attachment to at least one conduit. The fitting has a generally rectangular elongated unitary body with a back wall, opposed end walls, and two front corner walls defining elongated openings on three sides and an interior compartment. The end walls each have an outwardly extending hollow shank communicating with the interior compartment and having means for attaching to an end of a conduit. Three substantially planar cover plates attach to the body to cover the three elongated openings and enclose the interior compartment. One or more of the covers includes at least one shank formed thereon communicating with the interior compartment and having means for attaching to an end of a second conduit extending along a locus substantially perpendicular to the plane of the cover.
The present invention is distinguished over the prior art in general, and these patents in particular by electrical conduit box bodies having an axial conduit connecting stub or hub portion adjoined to the chamber of the body portion at one or both ends, and at least one perpendicular stub or hub portion defining passageways communicating with the chamber. The perpendicular stub or hub portion is adjoined to the chamber by a large outwardly curved interior radius that eliminates sharp corners at the intersection of the hub passageways with the body chamber and provides a maximum radius of curvature for wires or cables pulled through or passing through the chamber and stub or hub passageways.